An ammonia leak (NH3) occurred around 7:30 am in a nearly 40-year-old indoor skating rink undergoing renovations at the time. A major emergency response was deployed; on-site, first responders detected an “unbearable” odour within roughly 100 m of the facility. An 800-m safety perimeter encircled the rink and 200 individuals, including some 40 students from a nearby school, were evacuated within a radius extending 150 to 200 m. Rail traffic was suspended and the police recommended that local residents close their windows and turn off their ventilation systems. These safety measures were lifted around midday. The hole pierced in the pipe was plugged using a wood corner and the building was properly ventilated, while the sector remained confined out to a 30-m perimeter as this aeration took place.

The accident was caused by human error; in executing works with a borer, 4 workers damaged one of the floor’s cooling system pipes. Toxic releases severely affected one of the workers to a point of being hospitalised out of precaution for examination, along with a municipal employee and 2 other individuals. According to first responders, at no point was the surrounding population ever threatened. The 3 tonnes of refrigeration NH3 were being stored for the most part in on-site tanks. Based on calculations, NH3 concentrations in the building atmosphere should have registered between 8 and 10 ppm of NH3, or 30 times less than the hazard threshold evaluated at 300 ppm. The direct expansion refrigeration installations were replaced within a year by a new system relying on a glycol loop.